Static electricity buildup is common on electrically insulating articles, such as paper-rollers and apparatus, flooring materials, various synthetic resin articles, and on elements having an electrically insulating support. This static electricity buildup can cause various problems. These include jamming of paper in paper-feeding apparatus, dust accumulation, unpleasant electric shocks, or noise in electronic circuits.
In photographic elements, radiation-sensitive emulsions are usually coated on an insulating support, rendering the element susceptible to the buildup of static electric charge. This can cause a number of problems. Among the most serious of these is that the discharge of accumulated static charges exposes the radiation-sensitive layer of the element to light, causing marks on the element when developed.
In order to reduce the accumulation of static charge on elements with electrically insulating articles, the article is often coated with a layer containing an antistatic composition that increases electrical conductivity. Alternatively, the antistatic composition can be incorporated into the composition of the article or an existing layer of an element. Various materials have been used as antistatic compositions, such as polymers, surface active agents, salts, and combinations thereof.
A number of such antistatic compositions exhibit problems, especially when used in photographic elements. For example, they can cause fog or loss of photographic sensitivity. There is a need to provide antistatic compositions that effectively reduce the accumulation of static charge while exhibiting reduced susceptibility to disadvantages such as those described above.
Polyphosphazene antistatic compositions recently have been proposed in copending and coassigned application Ser. No. 087,480 filed Aug. 20, 1987, by Chen et al. In the copending application polyphosphazene is combined with a salt in order to form a conductive composition. This composition has been suggested for use in photographic antistatic layers. While a satisfactory antistatic composition, the material is somewhat tacky and not altogether suitable as an outer coating. Phosphazenes have also been disclosed for anti-static layers in Japanese Application No. 129882--Konishiroku published Dec. 11, 1987.
Phosphazene polymers have also been suggested for use where higher temperature polymers are desirable such as in gaskets for engines, in friction surfaces, and as membranes for separations of gases or liquids. Such uses would not require the addition of salt as the gasket or friction materials would not need to be conductive or have anti-static properties. In use as a gasket material, membranes, or friction surface, as well as in polymer film antistatic surface coats, it is advantageous that the polymer have good abrasion resistance, hardness, and strength. Therefore, it would be desirable if these properties could be improved for phosphazene polymers.
It has been disclosed in U.S. Pat. No. 4,218,556--Hergenrother et al that chlorophosphazene polymers can be cross-linked with tetraalkylorthosilicate. Great Britain Patent No. 1,052,388--Emblem et al discloses that phosphazene trimeric materials may be cross-linked with similar silicates. However, these cross-linked materials have the disadvantage that they are difficult and expensive to make, and are not believed to be abrasion resistant or tough. U.S. Pat. No. 4,026,839--Dieck et al discloses polyphosphazene polymer and silicone rubber blends that are fire retardant and may form foams. U.S. Pat. No. 4,668,762--Ogata and U.S. Pat. No. 3,304,270--Dickerson also discloses silicon-phosphorus containing polymer compositions. It has been disclosed in Exarhos et al, ".sup.31 P NMR Studies of Aqueous Colloidal Dispersions Stabilized by Polyphosphazene Adsorption", J. Am. Ceram. Soc., 71 (9) C-406-C-407 (1988), and Exarhos et al "Molecular Spectroscopic Characterization of Binding Interactions in Phosphazene Stabilized Alumina Dispersions", October 1987, presented at the Materials Research Society 23rd University Conference on Ceramic Science held in Seattle, Wash. Aug. 31, 1987, that polyphosphazenes will be utilized to stabilize alumina dispersions. In the process disclosed in the Exarhos et al articles a small amount of polyphosphazene is mixed with a large amount of large (0.4 micron diameter) aluminum particles. The purpose of the Exarhos et al processing is to form densified ceramic materials by utilizing polyphosphazene as a binder.
There remains a need for phosphazene polymers that have improved properties of cost, ease of formation, strength, and toughness. Transparency in strong phosphazene materials also is desirable.